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[BGL] Get all properties for edge
by Dmitry Bufistov 15 Dec '05

15 Dec '05

Hi, I have the following description of graph: ///////////////////////////code/////////////////////////////////// struct EdgeProperties { EdgeProperties(size_t ew = 0, size_t key = -1) : edge_weight(ew), edge_index(key) { edge_color = std::string("black"); } size_t edge_weight; std::string edge_color; size_t edge_index; //Key for distinguishing all input edges }; typedef adjacency_list< listS, ///<Store out&in -edges of each vertex in a std::list vecS, ///<Store vertex set in std::vector bidirectionalS, ///<Graph is directed with access to in & out edges VertexProperties, EdgeProperties, GraphProperties > Graph; ////////////////////////////////////////////////////////////////////////////// I have edge descriptor. I would like to get EdgeProperties structure for this edge. Many thanks in advance for help. Regards, --dima P. S. Special thanks to Douglas Gregor for previous answer it was really usefull for me

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Re: [Boost-users] serialization: loading std::map replacesexistingmapdata objects
by Peter Whaite 14 Dec '05

14 Dec '05

Robert Ramey <ramey(a)rrsd.com> wrote: > Which version of boost are you using? I believe this may have come up and > been addressed in 1_33_1? That might be it. I've been using CVS post 1_33, but its been a while since I installed from it. Right now compile of serialization fails so I cant check. I'll let you know once I do. Thanks.

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[boost-users] [ANN] Multi-State Mazes for C++ uses Boost
by Cromwell Enage 14 Dec '05

14 Dec '05

At long last, my multi-state mazes project has come to fruition! It's hosted at http://msmazes.sourceforge.net/ Description: Multi-State Mazes for C++ is a library for game developers that want to incorporate random multi-state mazes into their applications. A primer on the concept of multi-state mazes can be found at http://www.logicmazes.com/; the binary distribution includes a prototype implementation of the walkthrough arrow maze concept. Libraries used: * Boost.Graph * Boost.Random * Boost.Parameter (Please browse the documentation at http://msmazes.sourceforge.net/doc/api/ and comment on how I present the functions that use named arguments.) * Boost.MPL * Boost.DynamicBitset * Boost.uBlas (Particularly the vector and matrix class templates.) Have fun! Cromwell D. Enage __________________________________ Start your day with Yahoo! - Make it your home page! http://www.yahoo.com/r/hs

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boost error building with mingw
by Imran Akbar 14 Dec '05

14 Dec '05

Hi, I'm stuck here: scons: building targets... g++ -fno-common..... main-ng.exe .......... a bunch of stuff here then C:\Files\Programming\MinGW\bin..\lib\gcc\mingw32\3.4.2\...\..\...\..\mingw32\bin\ld:exe: cannot find -lboost_thread building terminated because of errors. I compiled boost again for MinGW, now have both vc and mingw-specific boost files in C:\Boost\lib, for example: boost_thread_mgw_mt-1_33.dll " ".lib boost_thread-vc71-mt-1_33.dll " ".lib etc. My environment variables are set correctly, and scons is pointing to the correct Boost path. Any ideas? Thanks, Imran

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[python] nested attributes, style question
by Malte Clasen 13 Dec '05

13 Dec '05

Hi, let's say we've got the following C++ classes: class position { public: float get_height() const; void set_height(float value); private: float height_; }; class object { public: position get_position() const; void set_position(const position& value); private: position pos_; }; This design is not fixed, but right now this is the starting point. When I added the boost.python interface to it using add_property(), I quickly noticed that using these classes feels somehow unpythonic: I cannot modify the height of the position of an object using obj.pos.height = x because get_position() returns the position by value, so the following set_height modifies a temporary instance of position. The work-around on the python side looks clumsy: position pos = obj.pos pos.height = x obj.pos = pos Now I wonder whether I just just go for public member variables on the C++ side and expose these using def_readwrite(). But this would couple the implementation to the interface. Moving the object class to another kind of position handling would be easy with the get/set-based interface using on-the-fly conversions, but nearly impossible with the public member. That's why I think of some kind of attribute proxy object that hides the C++ get/set stuff in a way that allows attribute manipulation on the python side but keeps interface and implementation separated on the C++ side. I'm not sure how this proxy would look like, but the idea feels somehow right... Is there a common solution to this problem? Does my proxy approach seem reasonable? Malte

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[string_algo] split input parameter not const?
by Thore Karlsen 13 Dec '05

13 Dec '05

split() is declared as follows: template<typename SequenceSequenceT, typename RangeT, typename PredicateT> SequenceSequenceT & split(SequenceSequenceT & Result, RangeT & Input, PredicateT Pred, token_compress_mode_type eCompress = token_compress_off); Is there a reason why Input isn't const? It would be nice to be able to construct an iterator range in the call to split(), like this: typedef iterator_range<string::const_iterator> range; vector<range> inputs; split(inputs, range(Begin, End), is_any_of("\r\n"), token_compress_on); It's the same for find_all(), ifind_all(), and probably others, so there might be a good reason for it that I'm missing. -- Be seeing you.

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Boost.Regex - problem with non-marking parenthesis
by Stuart Dootson 13 Dec '05

13 Dec '05

I have a regular expression that compiles & matches as expected, viz: boost::regex rxBlah("([a-z](_?[a-z0-9])*)_dvs", boost::regex_constants::icase); I would like to make the inner parentheses non-marking, so I modified the regex as below: boost::regex rxBlah("([a-z](?:_?[a-z0-9])*)_dvs", boost::regex_constants::icase); However, this throws a bad_expression exception on compilation, with the message "Invalid preceding regular expression". I've tested the second regex in another regex tool (The Regex Coach, http://weitz.de/regex-coach/) and it was accepted, and performed as expected - when presented with the text "a_dvs", it showed one capture, the text "a". So - help, what have I done wrong? Stuart Dootson

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How get the size of a stream< io::array_sink > memoryStream?
by Rodrigo Baroni 13 Dec '05

13 Dec '05

Hi all, How can I know the size of a stream< io::array_sink > memoryStream( buffer, size ) , after some operations that has filled the stream (the memory) ? Is there some way ? Example: //--------------- Compress the content of buffer to compressedBuffer---------------------- char buffer = "Helloooo compressed filter example!"; int SIZE = 10000; char compressedBuffer = new char [ SIZE ]; io::stream< io::array_source > bufferStream( buffer, std::strlen( buffer ) ); io::stream< io::array_sink > compressedBufferStream( &compressedBuffer, SIZE ); io::filtering_ostream compressFilterOutput; compressFilterOutput.push( io::zlib_compressor( ) ); compressFilterOutput.push( compressedBufferStream ); io::copy( bufferStream, compressedFilterOutput ); compressedBufferStream.flush( ); compressFilterOutput.reset( ); //----------------------------- How can I know the size of the compressedBufferStream, or compressedBuffer now? std::strlen( compressedBuffer ) gives me wrong value. Thanks in advance, Rodrigo Ferreira Baroni

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[serialization] Removing objects from an archive
by Przemyslaw Wojnowski 13 Dec '05

13 Dec '05

It helps a lot. But now I have another question. Could archive interface be changed/extended to support removing from an archive, so interface realization will be able to save/load/remove data selectively? If not, why? Przemek

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remove_if and transform_iterator
by Josue Gomes 13 Dec '05

13 Dec '05

Hi, Can transform_iterator be used in conjunction with remove_if algorithm? The compiler (vc7.1, vc8, g++) is refusing to compile this: #include <string> #include <utility> #include <vector> #include <functional> #include <cassert> #include <iostream> #include <boost/iterator/transform_iterator.hpp> std::vector<std::pair<std::string, int> > c; struct to_num { typedef int result_type; int operator()(const std::pair<std::string, int>& p) const { return p.second; } }; int main() { using std::make_pair; c.push_back(make_pair("A", 2)); c.push_back(make_pair("A", 3)); c.push_back(make_pair("A", 4)); c.push_back(make_pair("A", 15)); c.push_back(make_pair("A", 16)); c.push_back(make_pair("A", 17)); assert(c.size() == 6); std::remove_if( boost::make_transform_iterator(c.begin(), to_num()), boost::make_transform_iterator(c.end(), to_num()), std::bind1st(std::less_equal<int>(), 10)); assert(c.size() == 6); } Regards, Josue

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